Hi Andy,
I don't know how bad the chip is, but most of the national windscreen people now do a repair service. I had it done on a tin top a few years ago and the result was very good; an invisible repair, although TBH it wasn't in my line of sight.
They injected a resin into the crack under pressure and then used a UV lamp to cure the resin. They finish it off by scraping the excess resin off the screen with a razor blade before a final polish. It took about 15-20minutes in total and lasted for the remaining 18 months or so that I had the car.
May be worth considering, depending on how bad the damage is.
